Independent research reveals extent of Eskom’s violation of air quality laws

January 23rd, 2019, Published in Articles: EE Publishers, Articles: Energize

The Centre for Environmental Rights (CER) commissioned a study in late-2018 to assess Eskom’s state of (non)compliance with its air emission licences (AELs). It was found that – in its own monthly emission reports over a 21-month period – Eskom revealed nearly 3200 exceedances of its daily AEL limits for particulate matter (PM), sulfur dioxide (SO2), and oxides of nitrogen (NOx) at 13 coal-fired power stations.

Although Eskom is yet to respond in writing, the power utility did, however, confirm at a public participation meeting that it had received the report and that the exceedances occur due to start up and shut down stages at the power stations. It is questionable whether all 3200 exceedances could have resulted from start up or shut downs.

The analysis was conducted by Dr Ranajit Sahu, a consultant on energy and air quality issues based in Alhambra, California, USA. The findings in the report are based on Sahu’s education, professional training, and 28-years of experience in air pollution consulting and engineering, on behalf of US and international clients in the private and public sectors.

Click here to download the full report

As is clear from the analysis, all the Eskom coal plants for which Sahu was able to analyse data, except for Arnot, self-report significant numbers of exceedances for at least one pollutant.

Because the applicable limits in the AELs are quite lax compared to those recommended by the World Health Organisation, World Bank Group, or those adopted by China, for example, having any exceedances of the AEL limits is very troubling. Even perfect compliance with AEL limits allows for discharges of pollution at unhealthy levels.

Fig. 1: Number of exceedances of PM, SO2 and/or NOx AEL limits from April 2016 to December 2017.

Exceedances are even more troubling since most of these plants are located in area that is already significantly impaired from an air pollution standpoint (e.g., those in the Mpumalanga HPA). There was a high frequency of exceedances of certain pollutants at certain plants. Examples include:

  • Lethabo and Duvha had PM exceedances in 100% of reported months (21/21).
  • Kriel had PM exceedances in 95% of reported months (20/21). It is also worth noting that Kriel’s AEL limit for PM is higher than the 2015 Minimum Emission Standard (MES). I discuss MES further below.
  • Kendal had PM exceedances in 90% of reported months (19/21), with up to 48 exceedances in a single month (June 2016).
  • Matimba had SO2 exceedances in 100% reported months (20/20), with up to 65 exceedances in a single month (January 2017).
  • Medupi had SO2 exceedances in 81% of reported months (17/21).
  • Camden had SO2 exceedances in 62% reported months (13/21).
  • Matla had NOx exceedances in 76% of reported months (16/21), with up to 45 exceedances in a single month (June 2017). Matla’s AEL limit for NOx is also higher than the 2015 MES. Lethabo had NOx exceedances in 57% of reported months (12/21), with up to 57 exceedances in a month (April 2017).

Fig. 2: Number of PM AEL limit exceedances from April 2016 to December 2017.

Many plants with frequent exceedances have AEL limits that are higher than the 2015 Minimum Emission Standards (100 mg/Nm3 for PM, 3500 mg/Nm3 for SO2, and 1100 mg/Nm3 for NOx).

For example:

  • Matla’s PM limit of 125 mg/Nm3 was exceeded 82 times over the 21-month study period. Its NOx limit of 1200 mg/Nm3 was exceeded 482 times.
  • Kriel’s PM limit of 125 mg/Nm3 was exceeded 370 times.
  • Tutuka’s PM limit of 350 mg/Nm3 was exceeded 14 times.
  • Majuba’s NOx limit of 1500 was exceeded three times.
  • Hendrina’s NOx limit of 1200 was exceeded 11 times.
  • Grootveli’s PM limit of 350 mg/Nm3 (in 2016) and 200 mg/Nm3 (in 2017) was exceeded 48 times. Its SO2 limit of 4000 mg/Nm3 was exceeded 63 times. Its NOx limit of 1700 mg/Nm3 was exceeded 14 times.
  • Camden’s NOx limit of 1300 was exceeded 47 times.

Fig. 3: Exceedances of PM AEL limits by plant by month, April to December 2017.

Second, in addition to the number of exceedances reported here, many of these reported exceedances were significantly greater than the applicable AELs. For example, PM exceedances reached at least 500 mg/Nm3 at Duvha and Lethabo, 600 mg/Nm3 at Kriel, and 1500 mg/Nm3 at Grootvlei. At Grootvlei, 77% of the PM exceedances reached at least 400 mg/Nm3. At Kriel, 47% of PM exceedances were over 200 mg/Nm3.

Fig. 4: Number of SO2 AEL limit exceedances from April 2016 to March 2017.

While that is evident in a simple review of the hardcopy reports, Sahu did not conduct a quantitative analysis of the levels of exceedances because the data underlying the graphic reports was not made publicly available. It is recommended that electronic reporting of the underlying data be provided as this would provide a clear ability to conduct such an analysis. This is one of the major shortcomings of the current hardcopy reporting in addition to others noted below.

Fig. 5: Exceedances of SO2 AEL limits by plant by month, April to December 2017.

Third, many of the exceedances are frequent at particular plants as opposed to being sporadic, indicating that the underlying causes of such exceedances are not being addressed by Eskom. To the extent that the purpose of exceedance reporting is to identify the causes of such exceedances, and enable actions to mitigate underlying causes, I do not see evidence of such analysis or actions by the operators. Again, as noted, it is imperative that every effort should be made to eliminate to the greatest extent possible any exceedances in heavily populated areas already impaired by air pollution.

Fig. 6: Number of NOx AEL limit exceedances from April 2016 to December 2017.

Finally, in one particular aspect, the data presented here may be deceptive – specifically for the plants which have reported relatively fewer exceedances. The monthly reports do not contain information to clearly identify if the reason for relatively few exceedances is that the plant in question was operating well below capacity or with some units offline during the month.

Fig. 7: Exceedances of NOx AEL limits by plant by month, April to December 2017.

It is recommended that future monthly reports also provide plant and unit energy production and operating data. This would enable identification of the better-managed plants, normalising for capacity and energy production factors.

Contact Annette Gibbs, CER, Tel 021 447-1647,




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